Trump Jr. released his e-mails a day after the good-government group Common Cause filed complaints with Justice, Mueller and the Federal Election Commission.

The papers allege Trump Jr. and his dad’s campaign broke federal law by “soliciting a contribution from a foreign national,” and that “knowing and willful” violations can be prosecuted criminally.

Civil liability carries a fine of at least $5,000 while a felony conviction is punishable by up to five years in prison.

Larry Noble, a lawyer with the Campaign Legal Center, said, “I would think there’s evidence of a knowing and willful violation,” that could also expose Trump Jr., President Trump’s son-in-law Jared Kushner, and then-campaign manager Paul Manafort to a federal conspiracy charge.

But Georgetown law professor Jonathan Turley said a campaign-finance violation would be difficult to prove.

“The central question would be whether a tip or the disclosure of information could be treated as a campaign contribution. And the problem with that interpretation is that it would envelop a huge range of political speech,” he said.